Anchor strip for securing a conductor in a transformer coil

ABSTRACT

A thin elongated anchor strip inserted adjacent to a first layer of turns in a transformer coil which is wound on a spool. The strip has two sides and two ends and includes a slot for receiving the start conductor lead of the first layer of turns for anchoring the start conductor in the coil. The distance between one end of the slot and one end of the strip is such as to provide mechanical strength so that the strip will resist severance when the start conductor lead is extracted from the coil. The slot opens to one side of the strip with such a width as to facilitate the insertion of the start conductor lead into the slot during the winding of the coil. There are cut out portions at each corner of the slotted end of the strip to facilitate the extraction of the start conductor lead from the remaining turns in the first layer of the transformer. The width of the strip is approximately equal to the width of the spool and is substantially flush with opposite sides of the first layer of turns of the transformer coil.

United States Patent [191 Caltagirone [4 Nov. 18, 1975 ANCHOR STRIP FOR SECURING A CONDUCTOR IN A TRANSFORMER COIL [75] Inventor: Saverio Caltagirone, Danville, Ill. [73] Assignee: Construction Materials Division General Electric Company, Indianapolis, Ind.

[22] Filed: Apr. 5, 1974 [21] Appl. No.: 458,103

[52] US. Cl. 336/192 [51] Int. Cl. H01F 15/10 [58] Field of Search 336/192; 29/605; 1 174/138 F [56] References Cited 1 UNITED STATES PATENTS 2,122,894 7/1938 Sager 336/192 2,985,950 5/1961 Duman 3,368,176 2/1968 Rechel 3,626,151 12/1971 Them et a1. 174/138 F Primary ExaminerThomas .l. Kozma [57] ABSTRACT A thin elongated anchor strip inserted adjacent to a first layer of turns in a transformer coil which is wound on a spool. The strip has two sides and two ends and includes a slot for receiving the start conductor lead of the first layer of turns for anchoring the start conductor in the coil. The distance between one end of the slot and one end of the strip is such as to provide mechanical strength so that the strip will resist severance when the start conductor lead is extracted from the coil. The slot opens to one side of the strip with such a width as to facilitate the insertion of the start conductor lead into the slot during the winding of the coil. There are cut out portions at each corner of the slotted end of the strip to facilitate the extraction of the start conductor lead from the remaining turns in the first layer of the transformer. The width of the strip is approximately equal to the width of the spool v and is substantially flush with opposite sides of the first layer of turns of the transformer coil.

6 Claims, 4 Drawing Figures Patent Nov. 18, 1975 ANcIIoR STRIP FOR SECURING A CONDUCTOR IN A TRANSFORMER COIL BACKGROUND OF THE INVENTION This invention relates to an improved anchor strip for use with electrical coils. More particularly, it relates to an anchor strip having means for facilitating the extraction of a conductor lead from the coil and having means to avoid severance and disloding of the strip during the extraction of the conductor lead.

Electrical coils, such as transformers, have long been used to provide various functions such as voltage step up and down and ballasting gaseous discharge lamps.

.Coils have at least a start conductor lead and a finish conductor lead for connection to terminals on a terminal strip. Most coils are multi-turn, multi-layer devices made of insulated wire. The start conductor lead is derived from the first few turns of the first layer and the finish conductor lead is derived from the last few turns of the last layer. In order to restrain these conductor leads from unraveling the .turns it is necessary to secure them to the coil. This is especially true of intermediate sized wire such as that normally used in a ballast.

One such anchoring device used in the past was tape. After the conductor leads were pulled out and placed in the desired position with respect to the rest of the coil, they .were taped to the coil. It was found, however,

that the anchored location of the conductor was inex-.

act because the adhesive material on the tape deteriorated thus allowing the coil to unravel. Also a great deal of time was used in properly taping the conductor to the coil. I

Anchor strips were then developed with slots to hold the start and finish conductor leads in place. These anchor strips were placed within the transformer coil itself. The start anchor strip for securing the start conductor lead was placed nextto the winding spool and the first layer of conductorv was wound over the strip. One of the problems with someof the prior art anchor strips was that they were narrower than the width of the spool, about which the coil is wound, and thus also narrower than the first layer, thereby allowing the strip to slip out on Occasion. This happened especially when a spool, such as a paper type spool was used. Thelayers were wound tightly around this spool causing it to bow. A space occurred between the first layer and the paper stool often allowing the anchor strip to slide out.

- 2 strip because this end of the anchor strip was flush with the end of the transformer coil. This created a weak section between the slot and the end of the anchor strip. Quite often the anchor strip was severed at this 7 weak section when the start conductor lead was pulled away from the other turns of the coil by a reasonably gentle tug.

There was an opening from the slot to one side of the anchor strip to allow the start conductor lead to be easily inserted into the slot. In the prior art, this opening was very narrow so that sometimes the start conductor lead was not actually inserted into the slot. 7

Anchor strips usually are attached to one antoher, end to end, and are inserted onto a long spool and wound with wire. When the winding is complete, the spool is sawed into individual small spools at the point where the anchor strips are connected together. Since this distance between one end of the slot and one end of the anchor strip was very small, and since there was a certain tolerance in the sawing process, quite often the sawing process cut through the slot or cut so near to the slot so that the section between the slot and one end The shape of prior art anchor strip, especially the start. strip, also created problems during the extraction of the start conductor out of the coil. The prior art an- -chor strip had two ends and two sides with a slot situated near one end for receiving a start conductor lead.

The ends and sides of the strip met each other at right angles at the corners. These corners created problems when it was time to pull the first few conductor turns out from the coil to form a start conductor lead. A

small knifelike article was used to pull the start conducwas very, very weak. This, again, allowed for easy severance of the anchor strip between the slot and one end.

OBJECTS OF THE INVENTION Accordingly, it is one object of the invention to provide an improved anchor strip for securing a conductor lead in an electrical coil;

Another object is to provide an improved anchor strip for securing a start conductor lead and for facilitating the extraction of the start conductor lead from the remaining turns of an electrical coil.

Another object is to provide an anchor strip for use with an electrical coil for anchoring a conductor lead in the electrical coil and being substantially resistant to being severed by the conductor lead, especially during the extraction of the conductor lead from the remaining turns of the coil.

Another object is to provide an anchor strip which facilitates the insertion of an electrical conductor. lead intoa slot for anchoring the conductor to the coil.

Another object is to provide a low cost means for anchoring conductor leads in a coil.

SUMMARY OF THE INVENTION In accordance with one form of the invention there is provided an anchor strip for securing a conductor lead in a multiple turn coil. The anchor strip is elongated and has first and second ends and first and second sides. There is aslot in the strip for receiving the conof the anchor strip, this made very little. distance between one end of the slot and the end of the anchor ductor lead. One end of the slot is located a predeten mined distance from the first end of the strip for providing mechanical strength between the slot and the first end of the strip. A cut out portion is provided at the corner where the first end meets the first side for facilitating extraction of the conductor lead from the remaining turns of the coil.

BRIEF DESCRIPTION OF THE DRAWINGS The subject matter which is regarded as the invention is set forth in the appended claims. The invention itself, however, together with other objects and advantages thereof may be better understood by reference to the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a plan view of the anchor strip employing one form of the present invention.

FIG. 2 is a plan view of the plurality of anchor strips connected together employing one form of the present invention.

FIG. 3 is a perspective view of the coil and a portion of the anchor strip employing one aspect of the present invention.

FIG. 4 shows a cross section of FIG. 3 taken along line 4.

- DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularly to FIG. 1, there is provided an anchor strip 1 which is an elongated thin strip and, in the exemplitication embodiment, is made of a 0.015 inch thick super-calendered paper, however other suitable material may be used. The anchor strip 1 includes open portion 2 which extends into slot 3. Open portion 2 is large enough to facilitate placing a conductor lead, which in theexem plification embodiment is a start conductor lead, of an electrical coil into slot 3 for securing that conductor lead in the coil. This will be better understood in a later reference to FIG. 4. Again referring to FIG. 1, cut out portion 2 is formed by cutting strip 1 along lines 4 and 5. Protrusion 6 extends 'into opening 2 and is adjacent to slot 3. Another open area which will be better seen again in a later reference to FIG. ,4 is formed by cutting along line 7 of the strip.

Anchor strip 1 also includes first and second ends 8 and 15 respectively and first and second sides 12 and 13 respectively. The corner between first end 8 and second side 13 has been cut out as indicated along line 7. The corner between first end 8 and first side 12 forms cut out portion or open area 10. This is accomplished by cutting along lines 9 and 11. Another cut out portion 34 is formed by cutting the corner off between first side 12 and second end 15 along line 14. The funcbeen wound with a plurality of coils on a single long spool. Thus the spools and strips are cut simulta- ,neously. It may be seen in FIG. '2 that cut out portion 1 of strip 1 is adjacent to cut out portion 34 of the next adjacent strip before the cutting has taken place. If cut out portion 34 was not present, and it was replaced by right angle corners, some strip material could be left in cut out portion 10. This could happen because of variances in the cutting of the strips from one another. If

this happened, it would be more difficult for the start conductor lead to be extracted from the remaining turns of the coil. This will be better understood by reference to FIGS. 3 and 4.

Referring now to FIG. 3, there is shown coil 30 having a portion of spool 31 cut away to show a portion of anchor strip 1. FIG. 3 shows the start conductor lead, which are beginning turns 32, still inside the coil while FIG. 4 shows start'conductor lead 33 having been extracted from the coil.

Referring now to FIG. 4, which is a cross section taken along line 4 of FIG. 3, anchor strip 1 is situated with its ends 8 and 15 in contact with the top and bottom 24 and 25, respectively, of the electrical coil 30. The sides of the anchor strip 12 and 13, respectively, are in contact with opposite sides 20 and 21 of the first layer of turns of the coil. The coil in the exemplification embodiment is shown to have four layers of turns having insulation sheets 23 situated between adjacent layers. Any number of layers of turns may be used.

If at least two layers of turns are used, the first layer should have fewer number of turns than its adjacent, or second, layer. In FIG. 4, the second layer has two more turns than the first layer. By sacrificing turns in the first layer, there is a substantial distance between one end of slot 3, where conductor lead 33 is anchored, and first end f the anchor strip so that the anchor strip is substantially resistant to being severed, especially during the extraction of conductor lead 33 from the remaining turns of the coil.

As stated previously, FIG. 3 shows conductor 32 intact within the coil. After the coil has been wound, conductor 32 must be extracted from the coil to form start conductor lead 33, shown in FIG. 4, for connection to a terminal. This extraction may be done either manually or by machine. In any case there is tension placed on conductor 33'when it is pulled out. If this tension is too great and the distance between slot 3 and the end 8 of the anchor strip is too short, the anchor strip may be severed between slot 3 and end 8. Since the first layer of turns, shown in FIG. 4, has fewer turns than the second layer, the slot 3 may be positioned further from end 8 than was done in the prior art where all the layers had the same number of turns. This allows for morer anchor material between the slot and the end. Furthermore, by having the anchor strip width approximately equal to the width of the spool and thus sides 12 and 13 flush with the opposite sides 20 and 21 of the first layer of winding, it is more difficult for the anchor strip to be pulled out, or fall out, which is especially troublesome during the extraction of conductor 33. The first layer of wires 22 will hold anchor strip 1 down tight against spool 31 shown in FIG. 3, even if the spool 31 bows, especially since the anchor strip extends to the corners of the spool.

Cut out portion 10, which was described in reference to FIG. 1, is provided to facilitate the extraction of start conductor lead 33. Since the device (not shown) used to extract the lead 33 was often a sharp knife-like object, the anchor strip could be pulled out along with the start conductor lead if the cut out portion 10 was replaced by a solid corner of material. The sharp knifelike object (not shown) could come in contact with the strip and pull it out of the coil along with the start conductor lead. Furthermore, cut out portion 19, shown in FIG. 4, is provided for a similar purpose, that is, to facilitate the extraction of the start conductor lead. Again, there is an open area with no anchor strip material which might be caught by the knifelike object (not shown).

From the foregoing description of the exemplification embodiment of the invention, it will be apparent that many modifications may be made therein. For example, cut out portion 10 could be made larger or smaller than out out portion 19 depending on which side of the strip that it is desired for the conductor extraction to take place. It will be understood, therefore,

that the illustrativeembodiment is intended as an exemplification only and this invention is not limited thereto. It is also understood that it is intended in the appended claims to cover all modifications that fall within the true spirit and scope of this invention.

What i claim as new and desire to secure by Letters Patent in the United States is:

1. An electrical coil including an anchor strip for securing a start conductor lead to said electrical coil comprising:

at least first and second layers of conductor, each of said layers having a pluarality of turns;

said first layer having fewer turns than said second layer;

anelongated strip having first and second ends and first and second sides; said strippositioned adjacent to and contacting said first layer;

said strip including a slot having an opening to said second side;

said slot receiving said start conductor lead of said coil;

one end of said slot being a from said first end,

said predetermined distance being equal to or greater than the length of the diameter of the conductor in which said second layer exceeds said first layer so that said strip is substantially resistant to being severed by said start conductor lead especially during the extraction of said start conductor lead from the remaining turns of said coil; and

a cut out portion on said strip where said first end meets said first side for facilitating extraction of said start conductor lead from the remaining turns of said coil.

2. An electrical coil as set forth in claim 1 further including a cut out portion where said first end meets said second side for facilitating extraction of said start conductor lead from the remaining turns of said coil.

3. An electrical coil as set forth in claim 1 further including a spool about which said first layer is wound; the width of said spool being approximately equal to the width of said strip, wherein said first and second predetermined distance 6 sides of said strip are substantially flush with opposite sides of said first layer of conductor.

4. An electrical coil as set forth in claim 1 wherein said slot opening to said second side is of a sufficient size as to facilitate insertion of said start conductor lead into said slot.

5. A transformer coil including an anchorstrip for securing the start conductor lead of said coil comprising:

a thin elongated strip having first and second sides and first and second ends;

said transformer coil having at least first and second layers and having a plurality of turns of conductor; said first layer having fewer turns than said second layer;

said first and second sides of said strip being in substantial contact with opposite sides of said first layer;

a slot in said strip located a predetermined distance from said first end for receiving said start conductor lead; said slot including an opening to said second side;

first and second cut out portions adjacent to but on opposite sides of said first end for facilitating the extraction of said start conductor wire from the remainder of the turns of said coil.

6. electrical coil including an anchor strip for securing a conductor lead comprising:

at least one layer of conductor turns in said coil;

a thin strip contacting said layer of conductor turns and having first and second ends and first and second sides, the width of said strip being approximately equal to the distance between one side of said layer of conductor turns and another side of said layer of conductor turns for substantially fixing said strip in said coil;

a slot in said strip receiving the conductor lead, one end of said slot located a predetermined distance from said first end of said strip for providing mechanical strength between said slot and said first end; I

a first cut out portion where said first end meets said first side for facilitating extraction of the conductor lead from the remaining turns of the coil. 

1. An electrical coil including an anchor strip for securing a start conductor lead to said electrical coil comprising: at least first and second layers of conductor, each of said layers having a pluarality of turns; said first layer having fewer turns than said second layer; an elongated strip having first and second ends and first and second sides; said strip positioned adjacent to and contacting said first layer; said strip inCluding a slot having an opening to said second side; said slot receiving said start conductor lead of said coil; one end of said slot being a predetermined distance from said first end, said predetermined distance being equal to or greater than the length of the diameter of the conductor in which said second layer exceeds said first layer so that said strip is substantially resistant to being severed by said start conductor lead especially during the extraction of said start conductor lead from the remaining turns of said coil; and a cut out portion on said strip where said first end meets said first side for facilitating extraction of said start conductor lead from the remaining turns of said coil.
 2. An electrical coil as set forth in claim 1 further including a cut out portion where said first end meets said second side for facilitating extraction of said start conductor lead from the remaining turns of said coil.
 3. An electrical coil as set forth in claim 1 further including a spool about which said first layer is wound; the width of said spool being approximately equal to the width of said strip, wherein said first and second sides of said strip are substantially flush with opposite sides of said first layer of conductor.
 4. An electrical coil as set forth in claim 1 wherein said slot opening to said second side is of a sufficient size as to facilitate insertion of said start conductor lead into said slot.
 5. A transformer coil including an anchor strip for securing the start conductor lead of said coil comprising: a thin elongated strip having first and second sides and first and second ends; said transformer coil having at least first and second layers and having a plurality of turns of conductor; said first layer having fewer turns than said second layer; said first and second sides of said strip being in substantial contact with opposite sides of said first layer; a slot in said strip located a predetermined distance from said first end for receiving said start conductor lead; said slot including an opening to said second side; first and second cut out portions adjacent to but on opposite sides of said first end for facilitating the extraction of said start conductor wire from the remainder of the turns of said coil.
 6. electrical coil including an anchor strip for securing a conductor lead comprising: at least one layer of conductor turns in said coil; a thin strip contacting said layer of conductor turns and having first and second ends and first and second sides, the width of said strip being approximately equal to the distance between one side of said layer of conductor turns and another side of said layer of conductor turns for substantially fixing said strip in said coil; a slot in said strip receiving the conductor lead, one end of said slot located a predetermined distance from said first end of said strip for providing mechanical strength between said slot and said first end; a first cut out portion where said first end meets said first side for facilitating extraction of the conductor lead from the remaining turns of the coil. 